[CodeCompletion] Complete 'await' in expression position

rdar://problem/72199267

Author: rintaro

lib/IDE/CodeCompletion.cpp

@@ -5737,11 +5737,15 @@ static void addObserverKeywords(CodeCompletionResultSink &Sink) {
   addKeyword(Sink, "didSet", CodeCompletionKeywordKind::None);
 }
 
-static void addExprKeywords(CodeCompletionResultSink &Sink) {
+static void addExprKeywords(CodeCompletionResultSink &Sink,
+                            bool IsConcurrencyEnabled) {
   // Expr keywords.
   addKeyword(Sink, "try", CodeCompletionKeywordKind::kw_try);
   addKeyword(Sink, "try!", CodeCompletionKeywordKind::kw_try);
   addKeyword(Sink, "try?", CodeCompletionKeywordKind::kw_try);
+  if (IsConcurrencyEnabled) {
+    addKeyword(Sink, "await", CodeCompletionKeywordKind::None);
+  }
 }
 
 static void addOpaqueTypeKeyword(CodeCompletionResultSink &Sink) {
@@ -5808,7 +5812,7 @@ void CodeCompletionCallbacksImpl::addKeywords(CodeCompletionResultSink &Sink,
   case CompletionKind::ForEachSequence:
     addSuperKeyword(Sink);
     addLetVarKeywords(Sink);
-    addExprKeywords(Sink);
+    addExprKeywords(Sink, Context.LangOpts.EnableExperimentalConcurrency);
     addAnyTypeKeyword(Sink, CurDeclContext->getASTContext().TheAnyType);
     break;
 
@@ -6635,7 +6639,7 @@ void CodeCompletionCallbacksImpl::doneParsing() {
           addStmtKeywords(Sink, MaybeFuncBody);
           addSuperKeyword(Sink);
           addLetVarKeywords(Sink);
-          addExprKeywords(Sink);
+          addExprKeywords(Sink, Context.LangOpts.EnableExperimentalConcurrency);
           addAnyTypeKeyword(Sink, Context.TheAnyType);
           DoPostfixExprBeginning();
         }

test/IDE/complete_concurrency_keyword.swift

@@ -0,0 +1,46 @@
+// RUN: %target-swift-ide-test -batch-code-completion -source-filename %s -filecheck %raw-FileCheck -completion-output-dir %t -enable-experimental-concurrency
+
+// CHECK_DECL: NOT
+
+#^GLOBAL^#
+// GLOBAL: Begin completions
+// GLOBAL-DAG: Keyword/None:                       actor; name=actor
+// GLOBAL-DAG: Keyword/None:                       await; name=await
+// GLOBAL: End completion
+
+enum Namespace {
+    #^TYPEMEMBER^#
+// TYPEMEMBER: Begin completions
+// TYPEMEMBER-NOT: await
+// TYPEMEMBER-DAG: Keyword/None:                       actor; name=actor
+// TYPEMEMBER-NOT: await
+// TYPEMEMBER: End completion
+}
+
+func testFunc() {
+  #^STMT^#
+// STMT: Begin completions
+// STMT-DAG: Keyword/None:                       actor; name=actor
+// STMT-DAG: Keyword/None:                       await; name=await
+// STMT: End completion
+}
+
+func testExpr() {
+  _ = #^EXPR^#
+// EXPR: Begin completions
+// EXPR-NOT: actor
+// EXPR-DAG: Keyword/None:                       await; name=await
+// EXPR-NOT: actor
+// EXPR: End completion
+}
+func testClosure() {
+  func receiveClosure(_: () async -> Void) {}
+  receiveClosure { #^IN_CLOSURE?check=STMT^# }
+}
+
+func testFunc(x: Int = #^FUNCDEFAULTPARAM?check=EXPR^#) {}
+
+struct Something {
+  var x = #^MEMBERINIT?check=EXPR^#
+  func testFunc(x: Int = #^METHODDEFAULTPARAM?check=EXPR^#) {}
+}